WASHINGTON: US Secretary of State Rex Tillerson welcomed Chinese state councillor Yang Jiechi to Washington on Thursday as the world´s two most powerful diplomats talked trade, drugs and North Korea.

Yang is in Washington for two days at a time when relations between the top powers are dominated by the North Korean nuclear stand-off and President Donald Trump´s concerns about their trade imbalance.

His first port of call was the State Department, where he held closed door talks and had a working lunch with Tillerson, who is keen to keep China on board with a diplomatic push to force North Korea to negotiate its own nuclear disarmament.

"During the meeting, both sides reaffirmed President Trump and President Xi´s commitment to keep up pressure on North Korea´s illegal nuclear weapons and missile programs," State Department spokeswoman Heather Nauert said.

"They discussed the need to achieve a fair and reciprocal bilateral economic relationship, and shared approaches to stemming the flow of deadly narcotics," she added.

Washington is pushing China to cut off a flow of synthetic drugs and chemical precursors used in the production of narcotics to Latin America, as these are often smuggled into the United States and fuel an epidemic of opioid addiction.

China has agreed to support some new sanctions on Kim Jong-Un´s North Korean regime in support of Trump´s "maximum pressure: drive to force Pyongyang to abandon its quest to build nuclear-armed long-range missiles capable of hitting US cities.

"We hope that China will do more because we know that they can do more in terms of adhering to UN Security Council resolutions and sanctions that have been put in place against North Korea," Nauert said.

"We´re not seeking an adversarial relationship with the government of China. We are simply identifying actions that China has taken that undermine a rules-based order."

China´s long-standing trade surplus with the United States grew by 10 percent last year to 276 billion dollars, a sum Trump finds intolerable, and senior officials from both countries are in talks to try to head off talk of a trade war.

On Thursday´s talks, Nauert said that some diplomatic conversations are best kept private but noted that: "We have a frank exchange of ideas and information, and our viewpoints. Our president has made it very clear his concerns about trade imbalances, that´s the kind of thing that comes up."